1. Field of the Invention
The present invention relates to an internal combustion engine having a combustion heater.
2. Related Background Art
It is required that a warm-up of an internal combustion engine be speeded up at a cold time, and it is desirable to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine.
This being the case, for example, Japanese Patent Application Laid-Open Publication No.62-75069 discloses a technology of increasing a temperature of the so-called engine cooling water contained in an internal combustion engine body by utilizing combustion heat emitted from a combustion heater provided in a intake system separately from an internal combustion engine body and thereby speeding up the warm-up thereof and enhancing the performance of the car room heater.
Such an effect can be expected on one hand, however, in the internal combustion engine having the combustion heater, there might arise a serious concern about a thermal damage to a intake system structure on the other hand because of an excessive rise in a intake system temperature due to an influence by combustion heat emitted from the combustion heater.
It is a primary object of the present invention, which was devised under such circumstances, to provide a technology of preventing a thermal damage to a intake system structure due to combustion heat emitted from a combustion heater in an internal combustion engine having a combustion heater.
To accomplish the above object, according to a first aspect of the present invention, an internal combustion engine having a combustion heater may comprise a combustion heater operating when the internal combustion engine is in a predetermined operation state, and engine related elements warmed by heat of a combustion gas emitted by the combustion heater during a combustion to speed up a warm-up of the internal combustion engine and to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine, wherein fresh air becomes a combustion gas mixed intake air flowing toward the internal combustion engine body by mixing the combustion gas of the combustion heater with the fresh air entering a intake air passageway of the internal combustion engine, a temperature of the combustion gas mixed intake air is obtained, and a combustion state of the combustion heater is controlled based on this temperature.
xe2x80x9cwhen the internal combustion engine is in the predetermined operation statexe2x80x9d expressed herein may include a time when the engine is on the operation or after starting up the internal combustion engine at a cold time or at an extremely cold time, and when an heating value from the internal combustion engine itself is small due to e.g., a burned fuel quantity is small as well as when a heat receiving value of cooling water is thereby small. Then, the cold time implies that an outside air temperature is approximately xe2x88x9210xc2x0 C. to 15xc2x0 C., and the extremely cold time implies that the outside air temperature is lower than approximately xe2x88x9210xc2x0 C.
The xe2x80x9cengine related elementsxe2x80x9d may be engine cooling water and the internal combustion engine itself in which the combustion gas of the combustion heater is mixed in the intake air.
In the internal combustion engine having the combustion heater according to the present invention, the combustion gas emitted from the combustion heater operating when the internal combustion engine is in the predetermined operation state, is mixed in the intake air passageway of the internal combustion engine, whereby fresh air having flowed so far through the intake air passageway becomes a high-temperature combustion gas mixed intake air assuming combustion heat of the combustion gas.
Then, before the combustion gas mixed intake air enters the internal combustion engine body, a temperature of the combustion gas mixed intake air is obtained, and a combustion state of the combustion heater is controlled based on the thus obtained temperature, precisely on a value indicated by this temperature. Therefore, if this control is preferably carried out, an excessive rise in the intake system temperature due to the combustion heat can be restrained while speeding up the warm-up and enhancing the performance of the car room heater by utilizing the combustion heat of the combustion heater. It is therefore feasible to prevent the thermal damage to the intake system structure.
xe2x80x9cThe control of the combustion state of the combustion heaterxe2x80x9d expressed herein is to control factors, such as a force and a magnitude etc. of flames in the combustion heater, for determining the increase and decrease in the temperature of the combustion gas emitted from the combustion heater.
What can be exemplified as the xe2x80x9cfactorxe2x80x9d may be, for instance, quantities of the air and the fuel supplied for combustion to the combustion heater, etc. Particularly in the case of a combustion heater structured to increase a temperature of the engine cooling water by internally circulating the engine cooling water, what can be exemplified as the xe2x80x9cfactorxe2x80x9d may be, for instance, a flow rate, etc., of the engine cooling water. By controlling those factors, if the combustion quantity of the combustion heater augments, the flames gain a force to increase in magnitude with the result that the temperature of the flames rises. Then, the temperature of the combustion gas emitted from the combustion heater also rises. Consequently, the temperature of the combustion gas mixed intake air also rises.
Whereas if the combustion quantity of the combustion heater decreases, the flames lose the force to decrease in magnitude, and the temperature of the flames also drops, with the result that the temperature of the combustion gas emitted from the combustion heater drops. Consequently, the temperature of the combustion gas mixed intake air also drops.
Moreover, the warm-up is speeded up by utilizing the combustion gas of the combustion heater, which emits almost no smoke; in other words, contains no carbon, and therefore, it can be expected that the durability be more enhanced the by a prior art EGR, etc.
Then, since the combustion gas discharge passageway of the combustion heater communicates with the intake air passageway, the combustion gas of the combustion heater is again burned in the internal combustion engine. Subsequently, when the combustion gas can be, upon reaching the exhaust system of the internal combustion engine, purified by an exhaust catalyst normally provide in this exhaust system.
Moreover, apertures of the combustion gas discharge passageway and the air supply passageway of the combustion heater are not exposed directly to the atmospheric air, and hence an effect of reducing noises can be expected.
According to a second aspect of the present invention, an internal combustion engine having a combustion heater may further comprise a combustion gas mixed intake air temperature detecting element for obtaining a temperature of the combustion gas mixed intake air by actually measuring this temperature.
As xe2x80x9cthe combustion gas mixed intake air temperature detecting elementxe2x80x9d, e.g., a temperature sensor may be exemplified.
According to a third aspect of the present invention, an internal combustion engine having a combustion heater may further comprise a combustion gas mixed intake air temperature calculating element for obtaining a temperature of the combustion gas mixed intake air by calculating a temperature of the fresh air and a temperature of the combustion gas. As a combustion gas mixed intake air temperature calculating element, it is preferable to use, for example, a two-dimensional map consisting of a temperature of the fresh air before being mixed with the combustion gas and an exhaust temperature of the combustion gas.
xe2x80x9cThe two-dimensional mapxe2x80x9d is structured such that, for instance, the axis of ordinates indicates the exhaust temperature of the combustion gas while the axis of abscissa indicates the temperature of the fresh air before being mixed with the combustion gas, and a cross point therebetween indicates a temperature of the combustion gas mixed intake air. Further, for obtaining the combustion gas mixed intake air temperature corresponding to the rotational speed of the internal combustion engine, it is desirable that there be prepared a plurality of two-dimensional maps corresponding to the rotational speed such as, e.g., 1000 rpm, 2000 rpm, . . . . A read-only memory ROM incorporated into an engine electronic control unit ECU is previously stored with the above two-dimensional maps.
In the case of a combustion heater structured to increase a temperature of the engine cooling water by internally circulating the engine cooling water according to a fourth aspect of the present invention, in an internal combustion engine having a combustion heater, the calculation by the combustion gas mixed intake air temperature calculating element may, when executing a calculation, include the rotational speed of the internal combustion engine. In this case, the read-only memory ROM is previously stored with a specific arithmetic formula instead of the two-dimensional maps as a combustion gas mixed intake air calculating element.
For example, the following equation may be preferable as a xe2x80x9cspecific arithmetic formulaxe2x80x9d.
Tm={(1xe2x88x92xcex1)T1+kxcex1T2}/(1xe2x88x92xcex1+kxcex1) 
where
Tm: the calculated temperature of the combustion gas mixed intake air,
T1: the temperature of the fresh air before being mixed with the combustion gas,
T2: the exhaust temperature of the combustion gas,
Ne: the rotational speed
xcex1: the quantity of the fresh air for combustion of combustion heater (the quantity is obtained by arithmetic formula:xcex1=xcex10/Ne, where xcex10 is the compensation constant when the rotational speed Ne differs and is preferably, e.g., 0.2.), and
k: the compensation constant (when the fresh air xcex1 is supplied for the combustion upon an operation of the combustion heater, a combustion gas xcex1xe2x80x2 having a mass over the fresh air quantity xcex1 is emitted from the combustion heater with burning of the fuel for combustion in the combustion heater. The constant k is a numerical value determined taking into consideration an existence of this combustion gas xcex1xe2x80x2.)
Note that a combustion gas mixed intake air temperature calculating element may be constructed of a combination of the two-dimensional maps with the arithmetic formula.
Further, the calculated temperature Tm of the combustion gas mixed intake air is the value taking the rotational speed (intake air quantity) into consideration, and may therefore be said to be highly accurate corresponding to the operation state of the internal combustion engine at the time concerned.
According to a fifth aspect of the present invention, an internal combustion engine having a combustion heater, may comprise a combustion heater operating when the internal combustion engine is in a predetermined operation state, and engine related elements warmed by heat of a combustion gas emitted by the combustion heater during a combustion to speed up a warm-up of the internal combustion engine and to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine, wherein a combustion state of the combustion heater is controlled based on a temperature of fresh air itself entering an intake air passageway of the internal combustion engine.
The time xe2x80x9cwhen the internal combustion engine is in the predetermined operation statexe2x80x9d and xe2x80x9cthe engine related elementsxe2x80x9d expressed herein are the same as those stated according to the first aspect of the invention.
In this case, an intake air temperature can be optimally controlled because of taking into consideration the temperature of the fresh air itself, i.e., the temperature of the intake air before being mixed with the combustion gas.
According to a sixth aspect of the present invention, an internal combustion engine having a combustion heater, may comprise a combustion heater operating when the internal combustion engine is in a predetermined operation state, and engine related elements warmed by heat of a combustion gas emitted by the combustion heater during a combustion to speed up a warm-up of the internal combustion engine and to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine, wherein a combustion state of the combustion heater is controlled based on a temperature of the combustion gas itself emitted from the combustion heater. The time xe2x80x9cwhen the internal combustion engine is in the predetermined operation statexe2x80x9d and xe2x80x9cthe engine related elementsxe2x80x9d expressed herein are the same as those stated according to the first aspect of the invention.
In this case, since the temperature of the combustion gas itself is taken into consideration, the intake air temperature can be optimally controlled.
According to a seventh aspect of the present invention, it is desirable that a combustion quantity of the combustion heater be decreased when the temperature of the combustion gas mixed intake air flowing through the intake air passageway of the internal combustion engine, or the temperature itself of the fresh air, or the temperature itself of the combustion gas of the combustion heater is over a predetermined value.
xe2x80x9cThe predetermined valuexe2x80x9d given herein is a temperature enough to cause the thermal damage to the intake system structure.
In this case, considering the temperature enough to cause the thermal damage to the intake system structure, the combustion quantity of the combustion heater is decreased when the temperature of the combustion gas mixed intake air, or the temperature itself of the fresh air, or the temperature of the combustion gas of the combustion heater is high, and it is therefore feasible to restrain a decline of the durability of the intake system.
According to an eighth aspect of the present invention, an internal combustion engine having a combustion heater may comprise a combustion heater operating when the internal combustion engine is in a predetermined operation state, and engine related elements warmed by heat of a combustion gas emitted by the combustion heater during a combustion to speed up a warm-up of the internal combustion engine and to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine. The combustion heater includes an air passageway for supplying the air used for the combustion of the heater via an intake air passageway of the internal combustion engine, and a combustion gas discharge passageway for discharging the combustion gas emitted from the combustion heater into the intake air passageway. An air flow meter is provided at a portion, disposed upstream of a connecting point between the combustion gas discharge passageway and the intake air passageway, of the intake air passageway.
The time xe2x80x9cwhen the internal combustion engine is in the predetermined operation statexe2x80x9d and xe2x80x9cthe engine related elementsxe2x80x9d expressed herein are the same as those stated according to the first aspect of the invention.
The combustion heater is connected in bypass to the intake air passageway through the air supply passageway and the combustion gas discharge passageway.
Further, the air flow meter may be defined as an air resisting structure which hinders a flow of air flowing through the intake air passageway, and therefore a pressure of the air flowing out of the air flow meter is smaller than a pressure of the air entering the air flow meter. Namely, the air flow meter has a difference in the air pressure between an inlet and an outlet thereof.
Then, in this instance, since the air flow meter is provided at the portion disposed upstream of a connecting point between the combustion gas discharge passageway and the intake air passageway, the high-temperature exhaust gas of the combustion heater is not sucked in the air flow meter. Hence, the thermal damage to the air flow meter can be prevented.
According to a ninth aspect of the present invention, the air flow meter may also be provided between a connecting point of the intake air passageway to the air supply passageway and a connecting point of the intake air passageway to the combustion gas discharge passageway.
In this case however, as for a type of the air flow meter, it is required that, for example, a hot wire type or film type air flow meter with a less pressure difference between the inlet side and the outlet side be used. With this contrivance, even when the air flow meter as the air resisting structure is provided between the connecting point of the intake air passageway to the air supply passageway and the connecting point of the intake air passageway to the combustion gas discharge passageway, due to the existence of the air flow meter, it never happens that an ignition becomes hard to attain because of an air flow velocity not increasing inside the combustion heater.
According to a tenth aspect of the present invention, the air flow meter may be provided at a portion, disposed upstream of the connecting point between the air supply passageway and the intake air passageway, of the intake air passageway.
In this instance, as for the type of the air flow meter, there may be used an air flow meter with a pressure difference between the inlet side and the outlet side. The reason why this is so is that since there is provided no air flow meter along the intake air passageway between the connecting point of the air supply passageway to the intake air passageway and the connecting point of the combustion gas discharge passageway to the intake air passageway, with respect to the combustion heater connected in bypass to the intake air passageway, there is almost no pressure difference between the connecting point, serving as an inlet of the bypass, of the air supply passageway to the intake air passageway and the connecting point, serving as an outlet of the bypass, of the combustion gas discharge passageway to the intake air passageway, and therefore the air flow velocity becomes lower inside the combustion heater located between the air supply passageway and the combustion gas discharge passageway that form the bypass, and also constituting a part of the bypass in communication therewith. Accordingly, a well-conditioned ignition of the combustion heater is attained at all times.
According to an eleventh aspect of the present invention, an internal combustion engine having a combustion heater may comprise a combustion heater operating when the internal combustion engine is in a predetermined operation state, and engine related elements warmed by heat of a combustion gas emitted by the combustion heater during a combustion to speed up a warm-up of the internal combustion engine and to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine, wherein the intake air passageway is provided with a supercharger for pressurizing the intake air by forcibly intruding the intake air into the internal combustion engine body, and a combustion state of the combustion heater is controlled based on a pressure of the intake air in the intake air passageway when the supercharger is operated.
The time xe2x80x9cwhen the internal combustion engine is in the predetermined operation statexe2x80x9d and xe2x80x9cthe engine related elementsxe2x80x9d expressed herein are the same as those stated according to the first aspect of the invention.
What can be exemplified as the xe2x80x9csuperchargerxe2x80x9d may be a supercharger of which a driving source is a rotational force of an output shaft of the internal combustion engine, and a turbo charger, using an exhaust turbine, of which a driving force is a rotational force thereof.
According to a twelfth aspect of the present invention, a combustion quantity of the combustion heater may be decreased when the intake air pressure is equal to or higher than a set value. The xe2x80x9cset valuexe2x80x9d given herein is a value of a intake air pressure capable of exerting no burden upon an inter cooler normally set coupled with the supercharger as well as being a certain fixed intake air pressure value set for preventing an excessive rise in the intake air temperature due to an increase in the intake air pressure.
With this contrivance, even when the temperature of the intake air rises with the increased intake air pressure, the combustion quantity of the combustion heater is reduced corresponding thereto, and a preferable intake air temperature can be thereby gained. It is therefore possible to relieve the burden upon the inter cooler.
According to a thirteenth aspect of the present invention, the combustion quantity of the combustion heater may be decreased when the temperature of the combustion gas mixed intake air and the intake air pressure are respectively equal to or higher than specified values. In this case also, the burden on the inter cooler can be relieved. Note that the specified value given herein is the same as the predetermined value in the seventh aspect of the invention in the case of the temperature of the combustion gas mixed intake air, and the set value described above in the case of the intake air pressure.
According to a fourteenth aspect of the present invention, an internal combustion engine having a combustion heater may comprise a combustion heater, and engine related elements warmed by heat of a combustion gas emitted by the combustion heater during a combustion to speed up a warm-up of the internal combustion engine and to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine, wherein the combustion gas of the combustion heater is introduced into the intake air passageway of the internal combustion engine, and a combustion quantity of the combustion heater is decreased when the internal combustion engine is in a predetermined operation state with a small intake air quantity.
xe2x80x9cThe engine related elementsxe2x80x9d expressed herein are the same as that stated according to the first aspect of the invention.
xe2x80x9cThe small intake air quantityxe2x80x9d implies a case where the number of engine rotations is small, and a case where an aperture of a throttle valve is small, which are respectively explained in the following fifteenth and sixteenth aspects of the invention.
When the combustion gas of the combustion heater enters the intake air passageway, the fresh air becomes the combustion gas mixed intake air toward the internal combustion engine. The combustion gas mixed intake air is a mixed gas of the high-temperature combustion gas with the cold outside fresh air. Hence, if the quantity of the combustion gas contained in the combustion gas mixed intake air per unit capacity remains the same, and if a quantity of the fresh air is small, the temperature of the combustion gas mixed intake air rises. By contrast, if the quantity of the fresh air is large, the temperature of the combustion gas mixed intake air lowers.
In the internal combustion engine having the combustion heater according to the present invention, when the internal combustion engine is in the predetermined operation state with the small quantity of the air sucked inside the engine, i.e., with the small fresh air quantity, the combustion gas quantity in the combustion heater is decreased, and consequently the temperature of the combustion gas mixed intake air lowers. Accordingly, it is feasible to prevent the thermal damage from being exerted upon the intake system structure by controlling well the ratio of the combustion gas to the fresh air.
According to a fifteenth aspect of the present invention, the rotational speed may be set under a predetermined value when in the predetermined operation state.
xe2x80x9cWhen in the predetermined operation statexe2x80x9d expressed herein is the same as that stated in the fourteenth aspect of the invention.
xe2x80x9cThe predetermined value of the rotational speedxe2x80x9d is a specified rotational speed set slightly higher than another specified rotational speed. The former specified rotational speed is hereinafter referred to as a target rotational speed. The latter is hereinafter referred to as a limit rotational speed. The limit rotational speed is a rotational speed for ensuring an intake air quantity making the combustion gas mixed intake air temperature high enough to exert the thermal damage to the structure of intake system if the internal combustion engine is driven with this limit rotational speed, and if the combustion heater continues to operate with the driving of the internal combustion engine.
The reason why the target rotational speed is set higher than the limit rotational speed, is that an allowance of some extent is given to the rotational speed because it might be a trouble that the thermal damage is exerted on the structure of intake system upon reaching of the rotational speed to the target rotational speed.
According to a sixteenth aspect of the present invention, an aperture of a throttle valve may be set under a predetermined value when in the predetermined operation state.
xe2x80x9cWhen in the predetermined operation statexe2x80x9d expressed herein is the same as that stated in the fourteenth aspect of the invention.
xe2x80x9cThe predetermine value of the throttle valve aperturexe2x80x9d given herein is a numerical value for indicating a target throttle valve aperture set somewhat higher than a limit throttle valve aperture. The limit throttle valve aperture is a certain throttle valve aperture for ensuring an intake air quantity making the combustion gas mixed intake air temperature high enough to exert the thermal damage to the structure of intake system if the internal combustion engine is driven with this limit throttle aperture when the throttle valve is opened, and if the combustion heater continues to operate in this driven state.
The reason why the target throttle valve aperture is set higher than the limit throttle valve aperture is that an allowance of some extent is given to the throttle valve aperture because it might be a trouble that the thermal damage is exerted on the structure of intake system upon reaching of the throttle valve aperture to the target throttle valve aperture.
According to a seventeenth aspect of the present invention, the combustion heater may be stopped when in the predetermined operation state.
xe2x80x9cWhen in the predetermined operation statexe2x80x9d expressed herein is the same as that stated in the fourteenth aspect of the invention.
xe2x80x9cThe combustion heater is stoppedxe2x80x9d may imply, for example, a halt of a fuel pump for supplying fuels to combustion cylinders in which to produce flames serving as a combustion source of the combustion heater, and a halt of a blowing fan, or a combination thereof.
In the internal combustion engine having the combustin heater of the present invention, the combustion heater stops when in the predetermined operation state, i.e., when the quantity of the air sucked inside by the internal combustion engine is small. Then, if the combustion heater stops with a halt of the fuel pump, the fuel supply is cut off, and it follows that the flames are produced by only the residual fuel in the combustion heater. Normally, the residual quantity is small, and consequently, the duration of the flames is short. Hence, the heating value of the combustion heater is remarkably reduced. As a result, the thermal damage to the intake system structure can be prevented when the engine intake quantity is small.
Furthermore, when the combustion heater stops with the halt of the blowing fan, even if the flames leak out of the combustion heater, it is impossible to supply the air warmed by the flames toward the interior of the internal combustion engine spaced away from the combustion heater because of the blowing fan having stopped, and it follows that the combustion heater substantially does not operate.
Moreover, in the case of the combination type in which the combustion heater stops with the halt of the fuel pump and the halt of the blowing fan, it follows that the combustion heater does not operate completely.
According to an eighteenth aspect of the present invention, an internal combustion engine having a combustion heater may comprise a combustion heater, and engine related elements warmed by heat of a combustion gas emitted by the combustion heater during a combustion to speed up a warm-up of the internal combustion engine and to enhance a performance of a car room heater of a vehicle mounted with the internal combustion engine, wherein the combustion heater operates during not only an operation but also a halt of the internal combustion engine, a combustion gas of the combustion heater is introduced into a body of the internal combustion engine during the operation of the internal combustion engine, and the combustion gas of the combustion heater is introduced into an exhaust system of the internal combustion engine during the halt of the internal combustion engine.
xe2x80x9cThe operation of the internal combustion enginexe2x80x9d expressed herein implies a state where a piston reciprocates within the cylinder, and xe2x80x9cthe stop of the internal combustion enginexe2x80x9d implies a state where the piston does not reciprocate within the cylinder and remains stopped. Then, the combustion heater according to the present invention is contrived to operate solely independently if a proper operation switch for operating the combustion heater is turned ON even when the internal combustion engine is in the stopped state.
In the internal combustion engine having the combustion heater according to the present invention, during the operation of the internal combustion engine, the combustion gas of the combustion heater is introduced into the body of the internal combustion engine and therefore re-burned in the cylinders of the internal combustion engine while being supplied for speeding up the warm-up. Since the re-burned combustion gas of the combustion heater emits almost no smokes in other words, contains no carbon, an enhancement of the durability of the internal combustion engine can be expected.
Further, if the combustion heater operates during the halt of the internal combustion engine, the combustion gas emitted out of the combustion heater is flowed to the exhaust system of the internal combustion engine and discharged therefrom into the atmospheric air, which may be said to be sufficiently satisfactory as a measure against the exhaust gas of the combustion heater. Accordingly, since the treatment of the exhaust gas of the combustion heater is sufficient even during the stop of the internal combustion engine, it never happens that the combustion heater stops due to an insufficient treatment of the exhaust gas of the combustion heater, and the combustion heater can be independently operated. The combustion heat of the combustion heater is normally also utilized for warming the air blown from the car room heater. Therefore, if the combustion heater is made to work before getting in the car, the car room heater can be switched ON beforehand, so that the interior of the car room is warm and comfortable even at the cold time. Note that a process of previously switching ON and warming up the combustion heater may be termed pre-heating of the combustion heater.
Then, when the combustion heater is in a pre-heating state, the combustion gas emitted from the combustion heater is introduced into the exhaust system, and therefore, on the occasion of this introduction, there may be prepared an element for preventing the combustion gas from passing through the intake system of the internal combustion engine, and an element for sufficiently decreasing the temperature of the combustion gas so that the intake system, even when passing through the intake system, does not suffer from the thermal damage by the combustion gas. What can be exemplified as the element for decreasing the temperature of the combustion gas may be, e.g., an exhaust cooler. It is preferable that the exhaust cooler be disposed, e.g., in the combustion gas discharge passageway through which to connect the combustion heater to the intake system of the internal combustion engine.
According to a nineteenth aspect of the present invention, it is preferable that the combustion gas be discharged into the exhaust system by opening an exhaust gas re-circulation passageway constituting an EGR system.
xe2x80x9cThe EGR systemxe2x80x9d described herein is a system for returning a part of the exhaust gas to the intake system and introducing the exhaust gas again into the cylinders. xe2x80x9cThe exhaust gas re-circulation passagewayxe2x80x9d is a principal component of the EGR system and is a passageway for re-circulating the exhaust gas from the exhaust air passageway of the internal combustion engine to the intake air passageway thereof, which are connected in bypass to the cylinders of the internal combustion engine. Further, the exhaust gas re-circulation passageway has an EGR valve for controlling a flow rate of the re-circulated exhaust gas.
In the internal combustion engine having the combustion heater according to the present invention, in the case of a vehicle provided with the EGR system, the combustion gas of the combustion heater can be discharged to the exhaust system by using the exhaust gas re-circulation passageway, it is therefore possible to reduce the costs as well as providing the sufficient measure against the exhaust gas of the combustion heater even during the halt of the internal combustion engine.
These together with other objects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.